The present invention relates to apparatus for manipulating substantially cylindrical rolls which consist of convoluted paper, metallic foil, plastic foil, cardboard or the like, and more particularly to improvements in apparatus for confining such rolls in hollow cylindrical envelopes of the type having inner disc-shaped end walls (hereinafter called inner discs) adjacent to the end faces of a roll, a blank of wrapping material which surrounds the periphery of the roll and whose marginal portions are folded over the inner discs, and outer disc-shaped end walls (hereinafter called outer discs) which are adhesively secured to the folded-over marginal portions of the blank. Still more particularly, the invention relates to improvements in devices for supplying inner and/or outer discs to the disc-applying components of such apparatus so as to ensure predictable, rapid and inexpensive application of inner and/or outer discs.
It is already known to store differently dimensioned discs in a magazine and to operate the magazine in such a way that discs of selected diameter can be withdrawn therefrom by suction prior to delivery of removed discs into the range of devices which apply removed discs to the end faces of a roll or to folded-over marginal portions of a blank surrounding the roll and confining the inner discs. Reference may be had to U.S. Pat. No. 4,339,904 which discloses an apparatus whose magazine comprises a series of superimposed plates pivotable about a common vertical axis which is remote from the plates. The transfer mechanism for discs employs a horizontally extending suction-operated holding element which is designed to engage the topmost inner disc of a stack of discs on a plate which has been pivoted out of the magazine. The holding element transports the withdrawn inner disc to a position substantially at a level above a pressure-applying plate which constitutes the clamping head, and the inner disc is then pivoted into a vertical plane prior to being lowered into the range of the clamping head which attracts the lowered disc and applies it to the repective end face of a roll.
The just discussed prior apparatus exhibits a number of drawbacks. Thus, problems are likely to arise during removal of the uppermost disc of a stack of such discs on a selected plate of the magazine. Suction must be uniform over the entire area of a disc, not only as regards the distribution of suction ports but also as concerns the intensity of suction. As a rule, the intensity of suction must be quite pronounced which presents problems when the dimensions of the inner discs are relatively small so that numerous suction ports of the holding element remain exposed and thus affect the intensity of suction acting on a small-diameter disc. Moreover, the space requirements of the aforediscussed apparatus are considerable; thus, the apparatus must afford space whose length corresponds to twice the diameter of the largest disc, as considered in the direction of travel of rolls.